Aortic distensibility imaging
Aortic distensibility cine imaging captures cyclic ascending and descending aortic area change. CardiacNexus uses this modality for the pressure-normalized stiffness subset of Aortic stiffness and distensibility.
- Modality
- Aortic distensibility cine CMR
- UKB source
- Data Field 20210
- Pipeline step
- Ascending/descending aorta segmentation QC, area/diameter extraction, pressure-gated distensibility calculation, and aortic area visualization
- Outputs
- aortic_dist.csv, visualization/aorta/aortic_area.png, timeseries/aortic_area.png
- Maturity
- Source-audited modality page
Current pipeline role
The current source expects aortic_dist.nii.gz and seg_aortic_dist.nii.gz, where label 1 is ascending aorta and label 2 is descending aorta. It applies aorta_pass_quality_control, computes per-frame areas, derives equivalent maximum/mean/minimum diameters and maximum/mean/minimum areas, and writes the structural rows before attempting pressure-normalized distensibility.
Distensibility requires a configured pressure table and central pulse pressure column. Central pulse pressure below 10 mmHg is treated as invalid, and distensibility values above the current high-value threshold are skipped.
Current outputs
| Output family | Current rows | Source path | Notes |
|---|---|---|---|
| Equivalent diameters | ascending and descending maximum, mean, and minimum diameter rows | src/feature_extraction/Aortic_Distensibility_20210/eval_aortic_dist.py | equivalent diameter from area; legacy Maxium spelling is preserved |
| Aortic areas | ascending and descending maximum, mean, and minimum area rows | eval_aortic_dist.py | derived from label area and pixel spacing |
| Distensibility | ascending and descending pressure-normalized distensibility rows | eval_aortic_dist.py; configured pressure file | conditional on valid pressure and threshold checks |
| QC and time series | visualization/aorta/aortic_area.png, timeseries/aortic_area.png | eval_aortic_dist.py | shows max/min area frames and area curves |
Pressure denominator matters
Area change and distensibility are not interchangeable. Distensibility normalizes cyclic area change by central pulse pressure, so missing or invalid pressure data make pressure-normalized rows unavailable.
QC and interpretation caveats
The modality is sensitive to aortic segmentation quality, label consistency, cardiac phase sampling, pressure source configuration, and high-value filtering. Diameter rows are equivalent diameters derived from segmented area rather than direct caliper measurements.
Aortic distensibility cine values should not be silently combined with scout centerline geometry or LVOT root diameters. Each acquisition answers a different vascular question and carries different measurement assumptions.
Source audit
- Current input names, label meanings, QC call, area/diameter formulas, pressure gating, high-value skip behavior, output labels, and visualization paths were checked against
eval_aortic_dist.py. docs/data/output_column_inventory.ymlrecords theaortic_distartifact contract.- Textbook context boundary: broad clinical textbook context is not surfaced here because implementation and vascular stiffness literature context in the phenotype page are sufficient for draft rollout.
- Displayed figure provenance is recorded in
docs/data/figure_provenance.yml; permission and exact reuse wording remain pending for public release. A current-output local area/diameter curve remains the preferred replacement for public-release readiness.